1. Field of the Invention
The invention herein relates to sliding doors, windows and similar structures (hereinafter sometimes collectively referred to as "closures"). More particularly it relates to mechanisms for automatically closing such closures.
2. Description of Background Information
Sliding doors and windows are a feature of many homes, hotels, motels and recreational buildings. Most commonly, such doors and windows are formed in two or more parts which are fitted into a fixed frame, a fixed portion and a movable or "sliding" portion which moves in a track parallel to the fixed portion and is retracted across the fixed portion to enable a maximum of one-half of the doorway or window area to be opened. The movable part of the door or window normally slides horizontally. (The doors and windows are commonly termed "sliding", and in fact most of the windows, particularly in the smaller sizes, do slide in the tracks formed in the window frame. The large windows, and almost all of the doors, do not actually slide but rather roll on small wheels or casters which are fitted into the bottom rail of the door or window and roll in the tracks in the door or window frame. However, the common terminology of the industry is to label all of these as "sliding." However, as will be evident from the description below, the invention herein is most useful with those "sliding" doors and windows which actually roll on the small casters.)
(For brevity herein, the present invention and the background thereof will usually be described hereafter in conjunction with a sliding door such as a patio door. As will be noted below, however, it will be understood that the discussion is also applicable to sliding windows and other types of sliding or rolling doors besides patio doors, such as freezer locker doors, garage doors and the like.)
Because the doors move horizontally to open, they commonly remain in an open position unless manually closed, since there is no biasing, gravitational or other force to tend to return the door to the closed position. Persons in a hurry, or otherwise distracted, often unintentionally leave the doors open by being to rushed or forgetful to stop and close the door after opening and passing through it, even when that is unintended. However, such opened doors (or windows) cause significant problems.
1. Energy conservation--Opened doors and windows are major energy wasters. In the summer months cool air from an air conditioned room is lost through an opened door or window, thus requiring the air conditioning system to run longer and harder to make up the loss. Similarly, heated warm air in the winter is lost through opened doors and windows, again causing the heating system to run longer and harder to keep the house warm.
2. Personal and property security--An opened door or window is an invitation to prowlers to enter the home or for thieves to enter a hotel or motel room.
3. Physical safety--Sliding doors are commonly used in patio and courtyard areas, particularly in homes and motels, and often open directly to swimming pools, such as the backyard pools at many residences in the "Sunbelt" states from California to Florida. It is a tragic fact that each year many toddlers and small children wander unsupervised through open sliding patio doors into pool areas, fall into the pools and are drowned or, even if rescued, suffer severe brain damage from near drowning.
For these and other reasons, there has been considerable effort to develop mechanisms which can be attached to or incorporated into sliding doors and windows to cause the doors and windows to automatically be closed after they are opened to allow passage through the doorway. A wide variety of different kinds of mechanisms have been suggested to provide such automatic closure. However, all of the previous devices have had one or more of a variety of disadvantages:
1. Unsightly appearance, cumbersome in use, or difficult to attach to or incorporate into the door frame.
2. Reliance upon gravity to operate the mechanism, normally with activated by use of a suspended weight. This requires that the mechanism be disposed substantially vertically, which in many cases may not be possible or desirable.
3. Easily damaged or at least rendered temporarily inoperable if the door is deliberately or inadvertently closed by hand.
4. Lack of means for readily controlling the rate of closure, such that when new the doors may close faster than desired and when older may close more slowly than desired. In fact, older doors often do not close at all due to increased friction from worn caster wheels, dirt and oxidation in the track, and settling and warpage of the door frame.
Typical examples of prior art devices for door and window closure, each of which will be found to exhibit one or more of the above disadvantages, are found in U.S. Pat. Nos. 4,003,102 (Hawks et al.); 4,126,912 (Johnson); 4,884,369 (Tatham); and 4,891,911 (Yung). Numerous other examples may also be found in the patent and trade literature.
The need for reliable, efficient, and controllable door and window closing mechanisms has become imperative. Energy conservation demands that doors and windows be kept closed when heating and air conditioning systems are in operation. Personal and property security demands that doors and windows be kept closed to discourage entry by vandals and criminals. Finally, child safety demands that doors and windows be automatically closeable so that youngsters will not stray out of their houses into the dangers of unsupervised swimming pools, street traffic and other hazardous environments. In fact, to this latter end many states and municipalities have enacted or are considering laws and ordinances which require that homes, motels and other buildings where swimming pools are present be built with automatic door closers as a required part of the structure under the applicable building codes. It has also been proposed that existing structures where pools are present be required to be retrofitted with automatic door and window closing mechanisms. Consequently, the availability of an efficient, reasonably priced and controllable door and window closing system would be extremely advantageous and would overcome many of the objections that home owners, home buyers, contractors and the like currently have to installing and using the prior art devices currently available.